The Ryugado Cave upgrade project was launched about two years ago by local officials, including members of an association that formed to revitalize the cave and its surrounding areas to reverse a decline in visitors.

The newly decorated cave, one of the three largest in Japan, opened to the public on July 19.

“Tenkoseki” (heaven-descended stone), which is the largest stalactite in the cave, at about 11 meters, had been illuminated mainly with fluorescent and incandescent lights, but they were replaced with LED lights in blue, purple and other vivid colors.

“Kinen no Taki” (memorable waterfall), the largest waterfall in the cave, is lit up with blue LED lights.

The “Shichifukujin no Yakata” (house of seven gods of fortune) section is draped with projection mapping to trace the history of Ryugado Cave, which dates back about 175 million years.

To make it “Instagrammable” for people who post photos on Instagram and other social networking websites, free Wi-Fi is available inside. A fully air-conditioned rest area has also been set up at the exit.

“The theme is ‘adventure into your heart.’ We'd be happy if it becomes a space where you can feel various things in an active manner,” said Takayuki Nagashima, 57, who works for Ryugado Mirai, a company in charge of promoting the cave.

“I was attracted to the colorful illuminations and music. I’m glad that I came,” said Masako Yamada, 64, a nurse who visited the cave from Aomori Prefecture.

Admission is 1,200 yen ($11.30) for adults, 700 yen for junior high school students and 550 yen for elementary school students.